1. Field of the Invention
The present invention relates generally to tilting mechanisms suitable for use with chairs such as office chairs and, more particularly, to tilting mechanisms for the seat portions of such chairs as well as an interlocking tilting mechanism for supporting the seat portions to allow integral movement with the backrest.
2. Description of the Related Art
Recently, in the chairs used in the office many mechanisms which interlockingly tilt a seat portion with its backrest have been proposed and some of them are now in use.
However, most of the conventionally proposed interlocking mechanisms that tilt the seat portion together with the backrest, are arranged so that when the seat portion is sunk by the weight of the person using the chair the backrest leans backward and interlocks, or so that when a person leans into the backrest the seat portion sinks interlockingly at the same time that the backrest leans backward.
However, the posture with which a person sits on an office chair is not limited to a posture which can be coped with by the conventional interlocking mechanisms. For example, a person may sit on the chair while distributing his weight so that the front side of the seat portion sinks to its forward side.
In this case, there are problems in (1) that the chairs do not cope with the posture with the conventional interlocking mechanisms, (2) the forming cost of the constituent members is high, (3) there is a troublesome fabrication, or (4) a rough action is induced because of their complex structure even if an interlocking mechanism is installed.
In addition, the feeling of sitting on the chair becomes unpleasant because the abdominal region of the person sitting is compressed when he sits on the chair with a slouching posture if the seat portion is not sunk and forward.